Clean up initTestingHarnessWaitUntilDone

initTestingHarnessWaitUntilDone() did not differ functionally from
initTestingHarness(), which is usually called through description(). In
addition some tests that are in fact asynchronous (for example using
setTimeout) are missing initTestingHarnessWaitUntilDone calls. Rely on
description() to always call the platform test harness waitUntilDone
function, and remove redundant calls.
Add missing init calls in texture-size tests in 1.0.1 and reduce timeouts

These tests are asynchronous, but didn't call waitUntilDone correctly in
1.0.1 when run under the webkit test runner. Add the missing call. The
100 ms timeouts in these tests are also needlessly long and simply slow
down test execution, so fix that in 1.0.3+ versions of the test suite.
Restore initTestingHarness calls that were actually necessary
Speed up texture-size tests in 1.0.2 as well
Remove incorrect comment about canvas size check

The canvas is in fact sized to 50*50 pixels while the comment claimed it
to be the default 300*150 pixels. The fix is applied to all versions of
the conformance test suite.
Merge pull request #370 from NVIDIA/fix-drawingbuffer-test-comment

Remove incorrect comment about canvas size check
Merge pull request #366 from NVIDIA/init-testing-harness-cleanup

Clean up initTestingHarnessWaitUntilDone
Merge pull request #367 from NVIDIA/texture-size-wait

Add missing init calls in texture-size tests in 1.0.1 and reduce timeouts